Of growing concern in the landscape industry is the potential loss of millions of dollars in revenue due to an epidemic infestation of the glassy-winged sharpshooter.
The pest spreads Pierce's disease, a virtual death sentence for grape vines. Growers in northern California's wine country are calling for embargoes on all incoming plant materials from infested counties. The bug attacks grape vines, oleander and other woody ornamentals.
It is so abundant that the residue from its excrement gives the trees on which it feeds a 'whitewashed' appearance. Currently, eight counties in Southern California, as well as Kern, Fresno and Tulare counties, are infested. The pest is expected to spread north through the Central Valley, and eventually become established along the Coast and inland as far north as Mendocino County. Currently, infestation has afflicted all of the state's southern counties and is expected to progress north quickly.
Attempting to deflect that progress away from the wine country, California'Ds Department of Food and Agriculture has drafted a regulatory compliance agreement. It requires monitoring of nursery shipments from infested (southern) counties into clean (northern) counties.
Participation in the agreement is voluntary, but some nurseries have chosen instead to suspend shipment of potential host materials into 'clean' counties, costing them millions of dollars in sales.
Valley Crest Tree Company of Calabasas, California, for instance, will lose approximately $3 million this year, according to senior Vice-President, Robert Cruddup. He said, however, that the sacrifice of income is preferable to risking the health of their nurseries in clean counties.
If you see evidence of infestation on ornamental plants, or if you are moving plant material across county lines, contact your county agricultural commissioner. For more information, see the California Department of Food and Agriculture's website at http://plant.cdfa.ca.gov/gwss.